Mind Games (1989)

Rita and Dana Lund's marriage is in a crisis, Rita's frustrated from being just a housewife. To save their marriage, they set out for a camping trip through California with their son. At a camping site they meet the hitch-hiker Eric, who befriends their son.

Against Rita's will, Dana takes him with them, not knowing that he's a brutal psychopath who'll force their son to participate in his nightly trips of vandalism.